[dataway]

For a quick test, just disconnect the battery, tap the radiator, hoses, engine block with a soft mallet a few times to dislodge any existing bubbles and check fifteen minutes later to see if it's still bubbling ... if it is, hook the battery back up and get out the VOM.

Or pull the wire on the temp sensor. Temp sensor is about the only thing I can think of that would energize the coolant.

[rslarb]

I had the same problem. Recommend draining and flushing the radiator and replacing with purified water and some anti-freeze. There seemed to be a chemical reaction with distilled water and water wetter. That worked for me.